Many network transport protocols (like the Transmission Control Protocol (TCP)) feature adaptive congestion control mechanisms, in which the data transmission rate is dynamically adjusted to the network condition in order to utilize the available bandwidth optimally. For example, when available bandwidth is detected, the transport protocol increases the rate of data transmission. When network congestion is detected, the transport protocol reduces the rate of data transmission. Some network transport protocols use packet loss as an indication that network congestion has occurred. While this method is well suited to networks in which the predominant cause of packet loss is network congestion, it does not work well in networks in which a non-negligible amount of packet loss is caused by reasons other than network congestion. For example, in a wireless network, a significant source of packet loss is due to transmission errors caused by fluctuating signal strength, thermal noise and interference. Furthermore, despite the application of error control technique like forward error correction (FEC) and/or automatic retransmission requests (ARQ), there are often residual transmission errors that are not detected by the error control technique. For transport protocols using packet loss as an indication of network congestion, this will result in the sender unnecessarily reducing the data transmission rate, resulting in poor link utilization.
Various solutions have been proposed. For example, “De-randomizing” Congestion Losses To Improve TCP Performance over Wired-Wireless Networks” by Saad Biaz and Nitin H. Vaidya dated Sep. 27, 2004, ACM/IEEE Transactions on Networking June 2005, proposes one solution which relies on having a bottleneck network node that supports drop precedence.
As another example, “An Adaptive End-to-End Loss Differentiation Scheme for TCP over Wired/Wireless Networks” by Chang-hyeon Lim, and Ju-wook Jang IJCSNS International Journal of Computer Science and Network Security, VOL. 7 No. 3, March 2007 at page 72, proposes another solution, which uses the variation of round trip time (RTT) as the detection signature.
The inventors believe that other solutions for improving packet throughput can be provided.